Abstract: A coupling assembly for two aligned rotating shafts connected together by shear bolts. The coupling assembly includes a casing which limits the axial movement of the shafts by engaging a surface of one of the shafts after shearing occurs and the connection between the shafts has been severed. The casing is connected to the shaft in a manner that forms a chamber for housing a lubricating fluid to ensure lubrication of the relatively moving parts of the coupling assembly after shearing occurs. A circumferential taper is provided on one of the shafts to cause the lubricating fluid to generate hydrodynamic pressure after shearing occurs.